Step 3: check spread

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds only that the computation targets 'the data in the plan', which tells the agent it depends on prior workflow state, but says nothing about what happens if the plan lacks the needed data. Oddly, idempotentHint=false sits unreconciled against a read-only metric computation, and the description does not clarify it.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

One short sentence that front-loads the named metrics with no filler. Minor redundancy: 'Step 3' is repeated from the title, so the first two words spend a little space restating structured metadata.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no parameters and no output schema, the description is the only place an agent can learn what comes back, and it never says whether results are appended to the plan, returned inline, or persisted for build_report. The metric list is adequate for identification but leaves the output contract and failure behavior unspecified.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool takes zero parameters, so the baseline is 4 and there is nothing for the description to disambiguate. It correctly does not waste words on phantom arguments and instead points at the implicit input source, 'the data in the plan'.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description names a concrete resource (data in the plan) and enumerates the specific statistics produced: standard deviation, IQR, coefficient of variation, outliers and variance ratio. That is far more specific than 'analyze spread'. However, it never contrasts itself with nearby siblings such as describe, group_summary or correlation, so an agent must infer the boundary.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

'Step 3' plus the title 'Step 3: check spread' implies the tool belongs to an ordered workflow and should follow the earlier steps, which is real positional guidance. There is no explicit when-to-use/when-not statement and no named alternative for the case where the agent already has spread numbers from describe or group_summary.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.